A guidewire is used as a guide to track a catheter (or a micro-catheter) into targeted regions of the human vasculature or other body lumens. As the leading end of the catheter is pushed through blood vessels, it may encounter one or more branch vessels extending from a main vessel. In order for the catheter to select the correct branch vessel, the guidewire tip (which precedes the catheter tip into the main vessel) is manually torqued to select the desired branch vessel first. The catheter is then tracked over the guidewire into the selected branch vessel. This process may be repeated as desired until the catheter tip reaches the target location in the vasculature, whereupon a medical procedure may be performed.
A guidewire is a device that is made up primarily of a metallic coiled wire with a flexible leading segment. The degree of flexibility imparted to the wire depends upon the complexity of the vasculature for which it is intended. For example, a guidewire used in a neurovascular application should be highly flexible in order to maneuver through the extreme tortuosity found in the blood vessels in the brain. The two main functions of any guidewire are to 1) be able to track through tortuous blood vessels, and 2) be able to effectively select between branch vessels swiftly and effectively. Current guidewires do well in their ability to navigate through the vasculature; however, they lack in their ability to torque effectively and swiftly.
In most guidewires, typically as long as one hundred fifty centimeters (150 cm) or more, the flexible segment is constructed using two materials, namely coiled metallic wire fixed over a thin and flexible core metallic wire. Such construction provides a high degree of flexibility to the wire; however, it negatively affects the ability to torque the tip. Since one of the primary functions of the guidewire is to select branch vessels effectively, it is adversely affected by the lack of the ability to torque.
The generally practiced method of torqueing a guidewire is achieved by manually twisting a proximal end of the guidewire that remains outside of the patient's body (i.e., the user end). Due to the tortuosity of the vasculature coupled with the construction of the guidewire, the twisting of the proximal end of the guidewire at the user end does not necessarily translate proportionally to the distal end inside the body. This, in turn, may affect the user, e.g., making it difficult to access desired vessels required for the treatment.
Accordingly, there is a need for guidewires that provide both the ability to navigate inside complex and tortuous vasculature and the ability to torque a guidewire in order to select branch blood vessels swiftly and effectively.